The present invention is concerned with new polycarboxylic acid imidazolines, a process for the preparation thereof and cleaning agents containing them.
Cleaning agents, especially agents for washing the body and hair, as well as textile and dish washing agents but also industrial cleaning agents, are generally mixtures of tensides and tenside adjuvants. The tensides used for this purpose, as well as mixtures thereof with one another, consist of anionic, neutral, amphoteric and/or cationic surface-active materials. These surface-active materials contain a hydrophobic part, which consists of hydrocarbons, as well as a hydrophilic or polar part.
In the case of anionic tensides, the hydrophilic part consists of a negatively charged grouping, this being a sulfate, sulfonate, phosphate, phosphonate or carboxylate. These groupings can, however, also be attached to the hydrocarbon chains via a polyoxyethylene chain. Whereas the sulfonate- and sulfate- containing hydrocarbons are strongly anionically charged tensides, the phosphates, phosphonates and carboxylates are weakly anionic tensides.
In the case of the neutral tensides, the hydrophilic part consists of a polar, neutral grouping, for example of amine oxides, polyoxyethyl radicals, carbohydrates or polyoxyethylated carbohydrates.
In the case of the amphoteric tensides, the polar groups are zwitterions, i.e. these groups contain not only positive but also negative charges. These include especially betaines and protein condensates, as well as taurates.
In the case of the cationic tensides, the polar groups consist of mono-, di-, tri- and quaternary-substituted amines, all of which are positively charged in the neutral pH range. Whereas the mono-, di- and tri-substituted amines are weakly cationic tensides, the quaternary-substituted amines are strongly cationic.
The above-described tensides and mixtures thereof are problematical with regard to biological systems: in the case of tenside mixtures in the field of body cleansing agents, contact results between the formulation and the surface of the skin. Such tenside-containing mixtures can bind strongly or less strongly to the surface of the skin and have a negative influence on the microbial skin flora, which is the natural immunity system of the skin.
The exchange action of the tensides with the microbial skin flora can result in changes thereof and weaken them and, as a consequence, provide a point of attack for infections by foreign microbes and fungi. As a result thereof, allergies and dermatoses can manifest themselves, a fact which today is observed to an increasing extent.
In the case of the exchange action of the tensides with the skin, in many cases it can result in desiccation and desquamation and, after chronic exchange action, in microlesions.
After the cleaning of textiles, as well as of solid surfaces, which leave behind tenside-containing waste water, an exchange action results between the tensides and the micro-organisms of the waste water disposal plant, in which case these tensides can impair or destroy the viability of the microflora which break down materials.
Thus, tensides often act as true cell poisons. This applies to the strongly anionic and especially to the strongly cationic tensides.
Therefore, attempts have been made, by means of special mixtures of the described tensides with one another to obtain formulations which reduce the toxicity with regard to the aggressiveness of the strongly anionic, as well as of the strongly cationic tensides, i.e. to detoxify them.
This was achieved by the selection of favourable formulation ratios of neutral and amphoteric tensides with anionic tensides. The anionic tensides, especially the alkyl sulfates and the alkyl ether sulfates, are the most used surface-active materials in today's cleaning and care agents.
However, this detoxification is relative, i.e. the strongly anionic and the strongly cationic tensides can only be detoxified by up to a certain percentage.
Such relatively detoxified tensides are referred to as mild formulations.
The residual aggressiveness of the mild tenside formulations described in the prior art also manifests itself in that, in the case of contact of these materials with the cornea and mucosa of the eye, in normal cases, a strong burning sensation is experienced which can proceed as far as a true irritation of the eye.
Recently, attention has also been drawn to the problems of traces of such tenside-containing mixtures: in the case of oxyethylated products dioxans are formed as synthesis by-products, in the case of amines nitrosamines are formed and in the case of sulfates sulfones are formed, all of which are highly toxic or are potentially carcinogenic.
From H. Hitz et al., Parfumerie und Kosmetik, 64 16-21/1983, a new group of 2-alkylimidazoline-N-propionic acids (amphonyls) is known which are milder tensides than other amphoteric compounds. However, they give rise to considerable formulation problems since they are substantially very poor viscosity increasing materials and hydrolyse in alkaline media with cleavage of the imidazole ring.